# Turnover Number

In enzyme kinetics, we are interested to know how many maximum molecules of substrate can be converted into product per catalytic site of a given concentration of enzyme per unit time.

$k_{cat} =\dfrac{ V_{max}}{E_t}$

with

• $$k_{cat}$$ = Turnover number,
• $$V_{max}$$ = Maximum rate of reaction when all the enzyme catalytic sites are saturated with substrate and
• $$E_t$$ =Total enzyme concentration or concentration of total enzyme catalytic sites.

The units of Turn over number (kcat) are $$k_{cat}$$ = (moles of product/sec)/ (moles of enzyme) or sec-1.